Oximes crystal structures

In contrast with the Schiff base salen, salicylaldehyde oxime (79) (salox) complexes of Co have received comparatively little attention, but a series of bis-bidentate divalent complexes of the form iraiis-Co(sa 1 ox)2( D M SO)2 have been reported.343 The heterocyclic bidentate oxime violurate (lH,3H-pyrimidine-2,4,5,6-tetrone 5-oximate, Hvi) (80) and its /V-methyl (mvi) and /V,/V -dimethyl (dmvi) derivatives form high-spin divalent [Co(vi)]+ and Co(vi)2 complexes, whereas [Co(vi)3] is low spin.344 The mixed-ligand Co(dmvi)2(phen) complex is also low spin. The crystal structure of m-Co(pxo)2Br2 (pxo = 2-acetylpyridine-l-oxide oxime) is isostructural with the Ni11 relative.345 The dichloro complex also adopts a cis configuration. The tridentate dioximes 2,6-diformyl-4-methylphenol dioxime and 2,6-diacetyl-4-methylphenol dioxime (Hdampo) form binuclear complexes of the type (81a) and (81b) respectively.346 Cobalt oxide nanoparticles were prepared by... 

Starting from the Ni mrao-formyloctaethylporphyrin oxime complex, the meso-cyanooctaethylporphyrin N-oxide complex has been synthesized for the first time. The double addition of the nitrile oxide to 2,5-norbornadiene afford a porphyrin dimer, whose structure has been established by X-ray diffraction analysis (485). The 1,3-dipolar cycloaddition reaction of w< .so-tetraarylporphyrins with 2,6-dichlorobenzonitrile oxide yields isoxazoline-fused chlorins and stereoiso-metric bacteriochlorins. The crystal structure of one of bacteriochlorins has been characterized by X-ray diffraction (486, 487). 

Analysis of intermolecular interactions in the crystal structures of oxime molecules has been used to answer that question. In all available complex structures with one central metal ion we found no coordinative bonds from the oxime oxygen to the metal, but exclusively coordination between the nitrogen atom and the metal ion (data were retrieved from the Cambridge Crystallographic Database [14]). In a comprehensive study Bohm et al. investigated complexes of oxazoles, methoxypyridines, and oxime ethers with water [15]. On the basis of interaction energies obtained... 

In this chapter, we have looked at some of the intrinsic features of hydroxylamine, oxime and hydroxamic acid molecules. The insights obtained, particularly concerning the electrostatic potentials on their molecular surfaces, should provide a useful basis for proceeding to their gas phase and crystal structures and properties. 

By contrast, the X-ray crystal structures of both 2-formylbenzeneboronic acid (13) and its O-methyl oxime (14) reveal an intramolecular hydrogen bond in which one hydroxyl of the B(OH), unit truly acts as a hydrogen bond donor to a heteroatom of the ortho side chain <94MI621>. The hydrogen bond distance in the seven-membered ring is 1.562 A in 13 and 1.614 A in 14. 

The novel X-ray crystal structures of the following have all been reported 5-amino-4-(4-methoxyphenyl)-2-phenyl-7-(pyrrolidin-l-yl)-[l,6]naphthyridine-8-carbonitrile <1999AXC1670>, 5-amino-4-(4-diethylaminophenyl)-2-(4-hydroxy-phenyl)-7-(pyrrolidin-l -yl) [ 1,6]naphthyridine-8-carbonitrile <2001 AXC726>, 5-amino-4-(4-diethylaminophenyl)-2-phenyl-7-(pyrrolidin-l-yl)[l,6]naphthyridine-8-carbonitrile <2000AXC80>, and rotenone a-oxime <2003AXC392>. 

The ligands (20) contain a coordination site such as pyridyl or amino nitrogen, or a hydroxyl oxygen. Complexes of (20 T = NH2 and n = 2) with iron(II) have been studied recently.65 A copper(II) dimer (with bridging oxime groups) of (20 T = OH, n = 2 or 3) was described by Ablov and coworkers66 in 1972 and its crystal structure has been elucidated67 in 1974. 

Recently a series of condensation products of the oximes (7 R = H, Me R = Me, CH2Ph, Ph, p-MeC6H4) and (8) with amines have been prepared by reactions (2) and (3) respectively, and the species formed investigated by X-ray, NMR and IR studies.55 IR spectroscopic data obtained from the product of reaction (2) suggest structure (9) instead of (9 ) for the oxime (7), while lH NMR spectral data from the product of reaction (3) are in agreement with an equilibrium between (10) and (10 ). A crystal structure analysis indicates that the tautomers (9 R = Me, R = p-MeC6H4) and (10) are those preferred in the solid state.56 Furthermore, compound (9) is the sj n-Me.s n-Me isomer, while (10) is the anri-Me,an -acetyl isomer. 

Protonation of the oximate complexes OsHCl2(ON=CR2) (PTr3)2 produces OsHCl2(=N=CR2)(PTr3)2. An X-ray crystal structure of one derivative shows that it has a short osmium-nitrogen bond distance. This complex reacts with... 

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